Behold the Asteroid

This year has been mostly been in the news due to reasons which were more on the negative side. Out of the many reasons why the year has been a test to humanity, one is the continual passing of asteroids. Although most of them passed the Earth at a far-off distance, Earth had a close shave with some of these asteroids. But a large section of the population is not very familiar with what an asteroid is and how does it matter to us, Earthlings. Not all asteroids are to be feared. Asteroids are rich in rare minerals, which if mined & extracted could fetch multi-quadrillions in currency value back here on Earth. So let's go ahead and find out more about our love-hate relation with asteroids.

There are innumerable asteroids in our Solar System orbiting the Sun.

The Rock of the Space

Asteroids are boulders orbiting the Sun, with sizes ranging from some hundred metres to several kilometres. An asteroid is called a meteorite if it hits the Earth. If it completely evaporates in the Earth’s atmosphere before crashing on the surface, it’s called a meteor. People usually refer to meteors as ‘shooting stars’. Most meteorites are composed of silicates or a mixture of iron and nickel. In the past, some huge meteorites have struck Earth. Sixty-five million years ago, almost 90% of animal species were eradicated when a meteorite hit Yucatan, Mexico. Luckily, this happens very rarely! We owe this to Jupiter, which attracts many asteroids with its gravitational pull.

Dust particles in the early Solar System collided, forming larger clumps, known as planetesimals. These could grow by attracting more dust with their gravitational fields; some grew large enough to form the planets. Others remained, becoming the asteroids. Some of these asteroids collided with each other (and the early planets), fragmenting into smaller asteroids. Some of the collisions were slow enough that the asteroids merged, producing oddly shaped asteroids.

Like planets , asteroids also orbit the Sun.

Importance of locating Asteroid

Many asteroids form large rings or belts around the Sun. There are two asteroid belts in our Solar System: the main belt (or simply called the asteroid belt) between Mars and Jupiter, with thousands of asteroids (see picture below), and the Kuiper belt, named after its discoverer, a disk-shaped region that extends outside of Neptune’s orbit and contains countless asteroids and many dwarf planets, of which Pluto is the most famous. Most asteroids are found in the asteroid belt; however, there are asteroids that are not in that orbit, and they are called Near Earth Objects (NEO). Sometimes these NEOs can reach our planet Earth.

Asteroids are part of a group known as minor bodies. Asteroids, comets and meteoroids can provide valuable information about the evolution of our Solar System Additionally, there are small bodies called meteoroids, remnants of the formation of the Solar System. These meteoroids can be as small as a grain of rice. Meteoroids constantly meet Earth, producing what we see on Earth as ‘shooting stars’.

Smaller versions of asteroids are also called meteoroids

Interesting Facts about Asteroids

• The size of asteroids varies from the size of a speck of dust to the size of 945 kilometres (587 miles) in diameter! This is the dwarf planet Ceres – the largest discovered asteroid in the solar system.

• Most of the asteroids orbit the Sun between the orbit of Mars and Jupiter. This area is called the asteroid belt.
  Some of the larger asteroids can also be referred to as planetoids and minor planets. Ceres is the only dwarf planet to still keep its asteroid label.

• Asteroids are grouped into categories based on their composition – what the asteroids are made from.

• C-types, called chondrites, are made of clay and silicate rocks. These are by far the most common type of asteroid. These orbit furthest away from the Sun, mostly in the outer belt, so they have not been altered by the Sun’s heat.

• S-types, known as siliceous asteroids, are the stony asteroids made up of silicate rocks and nickel-iron mixtures. These are found mostly in the inner Asteroid belt.

• M-types are the metallic asteroids. These are mostly made up of nickel-iron.

• It is thought that asteroids are the leftover debris from the formation of the inner planets.

• The asteroids are irregularly shaped. This is due to their smaller size and small gravitational field. Objects with a large mass carry a large gravitational field. This gravitational force pulls inwards, bringing the larger objects (such as the planets and moons) into a mostly spherical shape. Asteroids lack the ability to do this as their gravity is low and just enough to hold the materials together, but not enough to make this round shape.

• The most famous asteroids are dwarf planet Ceres, Pallas – a huge 544-kilometre asteroid and Vesta – a very bright large object. These are all asteroids but also referred to as minor planets. Astronomers have been aware of them since the early 1800s.

• There is a very small chance of an asteroid colliding with our planet. Earth and other planets in the solar system were created through the process of objects crashing into one another to form larger worlds. These collisions are still happening, but luckily most of the larger items are gone, now making up parts of the planets we know. Luckily smaller objects would be destroyed by the Earth’s atmosphere if they orbited close to our home planet. Just in case there are many astronomers keeping an eye on the positions of any asteroids nearing Earth. These people map out the orbit path of these objects and can predict impacts well in advance.

• An asteroid colliding with Earth roughly 66 million years ago is thought to be one of the main factors bringing the dinosaurs to extinction.

• Roughly once every 2000 years and object about the size of a football field collides with Earth. The asteroid that hit Earth 65 million years ago would have been much much larger than this!

• If you grouped all of the known asteroids, their mass would still be smaller than that of our Moon.

Asteroids in the News

A big – very big – asteroid passed relatively close to Earth on April 29, 2020. Asteroid (52768) 1998 OR2 passed at a safe distance, at some 4 million miles (6 million km), or about 16 times the Earth-moon distance.

The asteroid 1998 OR2 passed by Earth on 29 April 2020

Very recently, an asteroid the size of an SUV passed 1,830 miles (2,950 kilometers) above Earth, the closest asteroid ever observed passing by our planet. The asteroid named 2020 QG, which was about 10 to 20 feet (three to six metres) long, passed above the southern Indian Ocean on Sunday, the 16th of August 2020, at 4:08 GMT (9:38am IST). 

An asteroid being tracked by NASA has a small chance of colliding with the Earth's atmosphere a day before the US election. The space rock, known as 2018VP1, is expected to come closest to the planet on 2 November - just hours before Americans head to the presidential polls.

Hope that was some good doze of asteroid information.

That's it for now. Stay Safe. Stay Healthy.